This conundrum has become known as “the Fermi paradox” and it just got a whole lot harder to answer this week after NASA revealed it had discovered seven Earth-sized planets in a single solar system, reports news.com.au.

There is a dark matter at the heart of the extraterrestrial debate.

First, let us remember that Earth is about 4.54 billion years old, humans are only 200,000 years old and our first orbital flight was in 1961. In other words, it took us 4,539,800,000 years to exist and another 199,944 years to get to space.

And so if we are to make contact with any other civilisation even remotely like ours, not only do we have to travel inconceivably vast distances but the timing has to be pretty spot on.

But it is not waiting for other civilisations to evolve that is the real problem.

The real problem is that any civilisation capable of space travel is almost certainly also capable of wiping itself out.

Consider this: Just a year after the Soviets put a man into space the world was brought to the brink of nuclear holocaust by the Cuban missile crisis.

As the legendary astronomer Carl Sagan observed: “Why are they not here? The temptation is to deduce that there are at most only a few advanced extraterrestrial civilisations - either because we are one of the first technical civilisations to have emerged, or because it is the fate of all such civilisations to destroy themselves before they are much further along.”

In other words it is highly likely there are other alien civilisations out there but it’s just as likely they have killed themselves.

Indeed, in the case of Earth we developed the capacity to destroy ourselves even before we managed space travel.

And if Germany had had atomic weapons at the same time as the Americans — as was suspected at the time — humans may never have achieved space travel at all. Civilisation could have been wiped out in 1945.

Yes, a quarter of a century before man landed on the moon, humankind had already invented the means of its own annihilation: a man-made nuclear chain reaction.